Torsades de pointes associated with high dose levomethadyl acetate (ORLAAM(R))

A patient undergoing management of heroin dependency with high dosages of t he long-acting methadone derivative, levomethadyl acetate HCI (LAAM; ORLAAM ((R))) developed a prolonged QTc interval and polymorphic QRS complexes on EKG consistent with torsades de pointes (TdP). The patient was taking other drugs known to prolong the QTc interval (fluoxetine and IV cocaine), and t hose known to antagonize the activity of the P450 enzymes responsible for t he metabolism of LAAM and its active metabolite (fluoxetine, cocaine and ma rijuana). No previous reports have appeared in the literature attributing t his adverse event to LAAM therapy; however, five similar cases have been re ported to the manufacturer. Animal studies indicate that LAAM and metabolit es prolong the action potential duration of myocardial cells. We propose th at predisposed patients on high doses of LAAM may be at risk for developing TdP. Patients being treated with LAAM should receive dosages consistent wi th guidelines and be evaluated for concomitant diseases, interacting drug t herapies, and EKG abnormalities. (C) 2001 by The Haworth Press, Inc. All ri ghts reserved.